Genes May Trigger Gambling in Women, Too

Action Points

Explain that genes appear to play an important etiologic role in disordered gambling in women as they do in men.

Note that this twin study did not find any evidence for shared environmental influences in disordered gambling.

Genes appear to play as big a role in disordered gambling among women as they do in men, with environmental factors having little or no influence, a study of twins has found.

Among 4,764 twins enrolled in the national Australian Twin Registry, around half of whom were women, the estimate of the proportion of variation in liability for disordered gambling due to genetic influences was about 50%, Wendy S. Slutske, PhD, of the University of Missouri in Columbia, and colleagues reported in the June issue of Archives of General Psychiatry.

"The results suggest that the susceptibility genes contributing to variation in liability for disordered gambling may also overlap considerably in men and women," they wrote.

Pathological gambling runs in families, which raises the question of whether familial transmission of the disorder can be explained by shared genes or shared environments, the researchers said. While most etiologic studies of pathological gambling have been conducted among men, nearly half of all patients in treatment for the disorder are women, the researchers said.

In the current study, participants, from 2,889 twin pairs in the Australian registry (mean age 38), were assessed through structured telephone interviews for disordered gambling and the similarity of their childhood environments. Many were frequent gamblers. Nearly all of the participants reported having gambled, with about half gambling at least once a month and about a third gambling at least once a week.

The overall prevalence of pathological gambling was 2.2% -- 3.4% among men and 1.2% among women.

About 12.5% had ever experienced one or more symptoms of pathological gambling -- 18.2% of men and 8.3% of women.

Using statistical models, the researchers found that the estimate of the proportion of variation in liability for disordered gambling due to genetic influences was 49.2% (95% CI 26.7 to 60.9).

They found no evidence for shared environmental influences contributing to variation in disordered gambling liability.

Nor was there any evidence of quantitative or qualitative sex differences in the causes of variation, the researchers said.

The findings are consistent with previous research. The Vietnam Era Twin Registry, for example, didn't find any evidence of shared environmental influences contributing to variation in disordered gambling liability, the authors noted.

That's similar to other meta-analyses of twin studies of alcohol dependence and major depression.

"In fact," they wrote, "decades of quantitative genetic research on psychopathology, personality, and cognition have consistently found that shared environmental factors do not explain significant portions of phenotypic variation for most traits."

They cautioned that shared family environmental factors may still be important in the development of disordered gambling since the effects of environmental factors may be genotype-dependent, or exposure to environmental factors may be correlated with genetic differences.

Still, they concluded that the results "suggest that much of the existing literature on disordered gambling that has been based upon research with men might also be generalized to women," adding that the discovery of specific genes and environments involved in the development of disordered gambling "remains an important direction for future research."

The current study was limited by the generalizability of its data to other cultures outside of Australia. That country was specifically chosen as the study site because it has a heavy gambling culture and higher prevalences of pathological gambling, the authors noted. The study is also limited in its generalizability because the age range of the cohort was narrow -- 32 to 43 years -- and the definition of disordered gambling had to be broadened in order to have adequate numbers for the sex analysis.

The study was supported by a grant from the National Institutes of Mental Health.

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